Optical connector plug

ABSTRACT

An optical connector plug includes a holder having a ferrule at one end thereof, a stop ring for supporting the ferrule in a predetermined direction, a plug frame for rotatably supporting and incorporating the stop ring in an axial direction, and a coil spring interposed between the holder and the stop ring, for energizing the ferrule to the front in the plug frame, wherein the holder and the stop ring have engaging portions with which they are mutually engaged, and an optical axis of the ferrule is adjusted in a single step by rotating the stop ring and fixing the plug frame or by rotating the plug frame and fixing the stop ring, and an adjusted position is fixed by pressure generated by pressing the spring to the holder and by using an adhering agent which is filled between the plug frame and the stop ring.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an optical connector plug whichis used for connecting optical cables for an optical communicationsystem.

[0003] 2. Description of the Related Art

[0004] An optical connector plug a, as a conventional art, as shown inFIGS. 9 to 12 comprises: an optical fiber cable b; an optical fiber cwhich is exposed by exfoliating a coating of a front end of the opticalfiber cable b; a microhole d which pierces an axis of the optical fiberc; a holder e; a ferrule f in which the optical fiber c penetrates themicrohole d and is fixed and which is armored and fixed at a rear endthereof by the holder e; a coil spring g which is armored by a rearportion of the holder e and is interposed between a stop ring i and anenlarging portion e₁ at a front end of the holder e; a pair of arcuateprojected bands h; the stop ring i, which is armored by the rear portionof the holder e from a substantially intermediate portion and on whichthe pair of arcuate projected bands h is symmetrically provided for acircumferential wall of the optical fiber c in the circumferentialdirection; four groove portions j which are provided at the enlargingportion e₁ of the holder e; two latching projected bands k which arelatched together to the four groove portions j to be opposed to eachother, at a substantially intermediate portion of an inside wall of theoptical fiber c; a pair of engaging holes 1 with which the pair of thearcuate projected bands h of the stop ring i is engaged; and a plugframe m which the pair of engaging holes 1 pierces to be opposed to eachother.

[0005] In the optical connector plug a as the conventional art, the stopring i and the plug frame m are combined and fixed and the stop ring iis unrotatable. To reduce an eccentric error, the ferrules f arepositioned, that is, the eccentricity between optical axes of theferrules f is corrected in advance upon assembly. However, in general, acore of the optical fiber is eccentric in some degree in terms of theaccuracy upon manufacturing. As shown in FIGS. 13 and 14, when a core oof an optical fiber c in one optical connector plug a is connected to acore p of an optical fiber c₁ in another optical connector plug a₁ toface each other, the optical axes of the cores o and p are madeeccentric and, thus, the loss of the connection is also caused.

[0006] Incidentally, referring to FIGS. 13 and 14, reference symbol fdenotes a ferrule of the one optical connector plug a and f₁ denotes aferrule of the other optical connector plug a₁.

[0007] Further, conventionally, an optical connector plug, as amechanism for correcting the eccentricity of optical axes of ferrulesafter assembly, is put into practical use. In the optical connectorplug, a positioning key is arranged to fix the ferrules to a determinedposition at which the loss of the connection is the most small byrotating the ferrules. However, since adjustment in a single step isimpossible, the precise correction cannot be performed against theeccentricity of the optical axes.

SUMMARY OF THE INVENTION

[0008] To solve the above-mentioned problems in the conventional opticalconnector plugs, it is an object of the present invention to provide anoptical connector plug, in which the eccentricity of optical axes offerrules integral with a stop ring can be adjusted in a single step andcan precisely be corrected by rotating the stop ring relative to a plugframe after assembling the optical connector plug, and the ferrules caneasily and certainly be fixed to a correcting position without using apositioning key.

[0009] To accomplish the above-mentioned object, according to a firstaspect of the present invention, there is provided an optical connectorplug comprising: a holder having a ferrule at one end thereof; a stopring for supporting the ferrule in a predetermined direction; a plugframe for rotatably supporting and incorporating the stop ring in anaxial direction; and a coil spring interposed between the holder and thestop ring, for energizing the ferrule to the front in the plug frame,wherein the holder and the stop ring have engaging portions with whichthey are mutually engaged, and an eccentric error of an optical axis ofthe ferrule is adjusted in a single step by rotating the stop ring andfixing the plug frame or by rotating the plug frame and fixing the stopring, and an adjusted position is fixed by pressure generated bypressing the spring to the holder.

[0010] According to a second aspect of the present invention, there isprovided an optical connector plug comprising: a holder having a ferruleat one end thereof; a stop ring for supporting the ferrule in apredetermined direction; a plug frame for rotatably supporting andincorporating the stop ring in an axial direction; and a coil springinterposed between the holder and the stop ring, for energizing theferrule to the front in the plug frame, wherein the holder and the stopring have engaging portions with which they are mutually engaged, and anoptical axis of the ferrule is adjusted in a single step by rotating thestop ring and fixing the plug frame or by rotating the plug frame andfixing the stop ring, and an adjusted position is fixed by pressuregenerated by pressing the spring to the holder and by using an adheringagent which is filled between the plug frame and the stop ring.

[0011] According to a third aspect of the present invention, there isprovided an optical connector plug comprising: a holder having a ferruleat one end thereof; a stop ring for supporting the ferrule in apredetermined direction; a plug frame for rotatably supporting andincorporating the stop ring in an axial direction; and a coil springinterposed between the holder and the stop ring, for energizing theferrule to the front in the plug frame, wherein the holder and the stopring have engaging portions with which they are mutually engaged, andthe entire of the stop ring is formed as a singlesubstantially-cylindrical structure, and the stop ring is rotated roundthe axis in the plug frame and is fit while it is prevented from themovement in the axial direction.

[0012] Preferably, in the optical connector plug, the engaging portionof the holder may be a latching groove, and the engaging portion of thestop ring may be an engaging projection.

[0013] Preferably, in the optical connector plug, the engaging portionof the holder may be a latching projection, and the engaging portion ofthe stop ring may be a latching groove.

[0014] Preferably, in the optical connector plug, a pair of latchingholes, which penetrates a circumferential wall of the plug frame to beopposed to each other, may be provided for the circumferential wall anda ring-shaped projected band for being fit into the latching hole may beprovided for a circumferential portion of the stop ring.

[0015] The ferrule is rotatably inserted in the center of the inside ofthe plug frame around the axis thereof and, thereafter, the coil springis interposed between the ferrule and the holder and the front portionof the stop ring is pressed and is fit into the plug frame. Then, thetarget portions at the peripheral edges in the ring-shaped projectedbands, which are arranged to the periphery of the stop ring, are fitinto the pair of latching holes that are formed by penetrating acircumferential wall of the plug frame to be opposed to each other. Inthis case, the engaging portions at the end of the stop ring are latchedtogether to the engaging portions of the holder and, then, theassembling operation is completed.

[0016] One optical connector plug having the above structure is fit intoan optical adapter from one opening of the optical connector. A ferruleof the one optical plug faces a ferrule of another optical connectorplug which is fit into the optical adapter from another opening. Thus,cores of both the ferrules are connected to face each other.

[0017] The eccentric error upon connecting both the ferrules is detectedby a well-known detector. If there is an eccentric error, the stop ringis rotated around the axis thereof while the optical connector plug isfit and hold into the optical adapter. Then, the stop ring is rotatedaround the axis thereof in a single step, relative to the plug frameand, consequently, the ferrules are rotated round the axis via theholder having the engaging portions which are engaged with the engagingportion of the stop ring.

[0018] The stop ring is rotated while the detector detects the eccentricerror which is caused by connecting the cores of the ferrules. Then, thestop ring stops rotating at the position at which the eccentric error isabsent or at the position at which the eccentric error is the smallest,thereby adjusting the eccentric error. By stopping rotating the stopring at the adjusted position, the stop ring is fixed by pressuregenerated by pressing the coil spring to the holder. Further, theadhering agent is filled between the plug frame and the stop ring,thereby fully being fixed.

[0019] In the present invention, as mentioned above, the eccentric errorcan be adjusted in a single step and the adjusted position can be fixedby rotating the ferrule, that is, the optical fiber in thecircumferential direction, relative to the plug frame. Therefore, theeccentric error can be reduced as much as possible and the connectingloss upon facing the both cores of the ferrules can greatly be reduced.

[0020] After assembling the optical connector plug, the ferrule, inother words, the optical fiber can be rotated at the same positionwithout the forward and backward movement by rotating the stop ringtogether with the coil spring and boot in the circumferential direction,relative to the plug frame. Thus, the eccentric error of the both corescan easily and accurately be adjusted, and the connecting loss uponfacing the both cores can greatly be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a longitudinal sectional view of an optical connectoraccording to a first embodiment of the present invention;

[0022]FIG. 2 is a sectional view taken on arrow A-A in FIG. 1;

[0023]FIG. 3 is a sectional view taken on arrow B-B in FIG. 1;

[0024]FIG. 4 is an exploded perspective view of the optical connectorplug in FIG. 1;

[0025]FIG. 5 is a side view of a plug frame of the optical connectorplug in FIG. 1;

[0026]FIG. 6 is a half sectional view taken on arrow C-C in FIG. 5;

[0027]FIG. 7 is a half sectional view of a stop ring in the opticalconnector plug in FIG. 1;

[0028]FIG. 8 is an exploded perspective view of an optical connectorplug according to a second embodiment of the present invention;

[0029]FIG. 9 is a longitudinal sectional view of a conventional opticalconnector;

[0030]FIG. 10 is a sectional view taken on arrow D-D in FIG. 9;

[0031]FIG. 11 is a sectional view taken on arrow E-E in FIG. 9;

[0032]FIG. 12 is an exploded perspective view of the conventionaloptical connector plug;

[0033]FIG. 13 is a sectional view in the case of fitting one opticalconnector plug, as a conventional art, into an optical adapter intowhich another optical connector plug is fit and of connecting cores ofthe optical adapter and the one optical connector plug so that both thecores face each other; and

[0034]FIG. 14 is an explanatory diagram showing an eccentric errorbetween a core of one optical connector plug as a conventional art and acore of another connector plug when both the optical connector plugsface each other.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] A description is given of an optical connector plug according toa first embodiment of the present invention with reference to thedrawings.

[0036]FIG. 1 shows a longitudinal sectional view of an optical connectoraccording to a first embodiment of the present invention, FIG. 2 shows asectional view taken on arrow A-A in FIG. 1, FIG. 3 shows a sectionalview taken on arrow B-B in FIG. 1, FIG. 4 shows an exploded perspectiveview of the optical connector plug in FIG. 1, FIG. 5 shows a side viewof a plug frame of the optical connector plug, FIG. 6 shows alongitudinal half-sectional view taken on arrow C-C in FIG. 5, FIG. 7shows a half sectional view of a stop ring in the optical connectorplug, and FIG. 8 shows an exploded perspective view of an opticalconnector plug according to a second embodiment of the presentinvention.

[0037] According to the first embodiment of the present invention, asshown in FIGS. 1 and 4, an optical connector plug 1 mainly comprises aferrule 2 which is fit and fixed into a rear end of a holder 6; a coilspring 3; a stop ring 4; a plug frame 5; and the holder 6.

[0038] As shown in FIG. 1, in the ferrule 2, an optical fiber 8 a isformed by exfoliating a coating of one end of an optical fiber cable B.The ferrule 2 is inserted into a microhole 7, which is inserted into acore of the optical fiber 8 a and is fixed by adhering. The holder 6 iscylindrical-shaped and one end portion (fit into the ferrule 2) of theholder 6 has formed at a cylindrical enlarging portion 6 a as shown inFIG. 4. A plurality of, e.g., four latching grooves 9 a, 9 b, 9 c, and 9d, as an engaging portion 9, are formed at a peripheral surface of theenlarging portion 6 a in a circumferential direction thereof atpredetermined intervals, as shown in FIGS. 2 and 4.

[0039] Referring to FIGS. 1 and 7, the stop ring 4 is formed as a singlesubstantially-cylindrical structure. A hook portion 10 of thering-shaped coil spring 3 is formed, at an inside wall of the stop ring4 at the front side thereof, to be directed to a front side (to bedirected to the left in FIGS. 1 and 7). Both ends of the coil spring 3are hooked to a rear end surface of the enlarging portion 6 a of theholder 6 and the hook portion 10, and the coil spring 3 is armored by arear portion of the enlarging portion 6 a in the holder 6.

[0040] Referring to FIGS. 1, 2, 4, and 7, at one end of the stop ring 4,a pair of engaging projections 11 a and 11 b, as an engaging portion 11which is engaged with a latching grooves 9 a to 9 c of the holder 6, isprojected ahead to be opposed to each other. Incidentally, three or fourenlarging projections may be provided corresponding to the number oflatching grooves of the holder 6, e.g., four, and the position of thelatching grooves.

[0041] Referring to FIGS. 1, 3, 4, and 7, at the periphery on the frontside of the stop ring 4, a ring-shaped projected band 12 is fit into apair of latching holes 13 and 13 a of the plug frame 5, which will bedescribed later. As shown in FIG. 1, the projected band 12 can easily befit into the latching portions 13 and 13 a by pressing the stop ring 4into the plug frame 5 from the opening at a read end thereof. Theprojected band 12 has a front surface inclined, as a guide surface 12 a,and a rear surface oriented in the vertical direction, as a latchingsurface 12 b, in order to prevent the stop ring 4 to move in the axialdirection after the fitting of the projected band 12. A chamfer 4 a forfacilitating the rotation is provided at a circumferential portion of arear end of the stop ring 4.

[0042] Referring to FIGS. 1, 3, 5, and 6, in the plug frame 5, the pairof the latching holes 13 and 13 a, which fits a circumferential end ofthe ring-shaped projected band 12 in the stop ring 4 into a rear portionof a circumferential wall 5 a (in FIG. 6), is pierced long in adirection vertical to the core to be opposed to each other.

[0043] An inside wall 14 for abutting a front surface of the enlargingportion 6 a of the holder 6, against elastic power of the coil spring 3,is provided close to a front end from a substantially intermediateportion in the plug frame 5. The ferrule 2 is inserted into a centralhole 15 of the inside wall 14 movably in the axial direction. A frontend of the ferrule 2 is projected from the plug frame 5 to the front.Incidentally, in FIG. 1, reference numeral 16 denotes a boot whicharmors a rear end of the stop ring 4 and the optical fiber cable 8.

[0044] As shown in FIG. 1, in the optical connector plug 1, in a statein which the optical fiber cable 8 and the holder 6 are inserted in thestop ring 4, both ends of the coil spring 3 are hooked to the rear endsurface of the enlarging portion 6 a of the holder 6 and the hookportion 10 of the stop ring 4, and coil spring 3 armors the rear of theholder 6. The front of the stop ring 4 is pressed in the plug frame 5from the opening at a rear end of the plug frame 5, and the engagingprojections 11 a and 11 b of the stop ring 3 are engaged with thelatching grooves 9 a and 9 c or with the latching grooves 9 b and 9 d ofthe holder 6.

[0045] Further, the stop ring 4 is pressed, thereby, the ring-shapedprojected band 12 of the stop ring 4 is fit into the latching holes 13and 13 a of the plug frame 5, and the assembling operation is finished.As shown in FIG. 3, the guide surface 12 a and the latching surface 12 bin FIG. 7, as symmetrical peripheral portions, of the ring-shapedprojected band 12 are fit into the latching portions 13 and 13 a. Hence,after the assembling operation, the stop ring 4 can be rotated round theaxis, relative to the plug frame 5. The rotation of the stop ring 4enables the holder 6 and the ferrule 2 to rotate round the axis. In thiscase, the ferrule 2, the coil spring 3, the stop ring 4, and the boot 16are integrally rotated 360°.

[0046] The eccentric error of the ferrule 2 is adjusted in a single stepby using the above rotating members and, thereafter, the adjustedposition is fixed by pressure generated by pressing the coil spring 3 tothe holder 6. However, the best adjusted position is moved upon movementby using the boot 16 or the like after the assembling operation and onlythe pressure generated by the coil spring 3 does not enable the adjustedposition to completely be fixed. Consequently, an adhering agent (notshown) is filled and is fixed between the stop ring 4 and the plug frame5.

[0047] Although the plug frame 5 is fixed as mentioned above and thestop ring 4 is rotated in the adjustment in a single step, the stop ring4 may be fixed and the plug frame 5 may be rotated.

[0048] When the plug frame 5 is fixed and the stop ring 4 is rotated,the ferrule 2 is always rotated at the same position by the operation ofthe coil spring 3. Further, the ferrule 2 is not moved forward andbackward and the pressure of the coil spring 3 is uniform.

[0049] Accordingly, the pair of optical connector plugs 1 is connectedvia an optical adapter, the ferrules 2 can always be faced each otherwith uniform pressure.

[0050] According to the first embodiment, the latching grooves 9 a to 9d as the engaging portion 9 of the holder 6 are engaged with theengaging projections 11 a and 11 b as the engaging portion 11 of thestop ring 4. However, according to the second embodiment, as shown inFIG. 8, the engaging projections 9 e and 9 f as the engaging portion 9of the holder 6 may be engaged with the latching grooves 11 c and 11 das the engaging portion 11 of the stop ring 4.

[0051] Although the first and second embodiments relate to the opticalconnector plug having a core in the center of the optical fiber 8 a, thepresent invention can be applied to an optical connector plug having apair of stress applying portions at both sides of the core, namely, apolarization-preserving optical connector plug.

[0052] Drawings [FIG. 1], [FIG. 2], [FIG. 3], [FIG. 4], [FIG. 5], [FIG.6], [FIG. 7], [FIG. 8], [FIG. 9], [FIG. 10], [FIG. 11], [FIG. 12], [FIG.13], [FIG. 14]

What is claimed is:
 1. An optical connector plug comprising: a holderhaving a ferrule at one end thereof; a stop ring for supporting theferrule in a predetermined direction; a plug frame for rotatablysupporting and incorporating said stop ring in an axial direction; and acoil spring interposed between said holder and said stop ring, forenergizing said ferrule to the front in said plug frame, wherein saidholder and said stop ring have engaging portions with which they aremutually engaged, and an eccentric error of an optical axis of theferrule is adjusted in a single step by rotating said stop ring andfixing said plug frame or by rotating said plug frame and fixing saidstop ring, and an adjusted position is fixed by pressure generated bypressing said spring to said holder.
 2. An optical connector plugcomprising: a holder having a ferrule at one end thereof; a stop ringfor supporting the ferrule in a predetermined direction; a plug framefor rotatably supporting and incorporating said stop ring in an axialdirection; and a coil spring interposed between said holder and saidstop ring, for energizing said ferrule to the front in said plug frame,wherein said holder and said stop ring have engaging portions with whichthey are mutually engaged, and an optical axis of the ferrule isadjusted in a single step by rotating said stop ring and fixing saidplug frame or by rotating said plug frame and fixing said stop ring, andan adjusted position is fixed by pressure generated by pressing saidspring to said holder and by using an adhering agent which is filledbetween said plug frame and said stop ring.
 3. An optical connector plugcomprising: a holder having a ferrule at one end thereof; a stop ringfor supporting the ferrule in a predetermined direction; a plug framefor rotatably supporting and incorporating said stop ring in an axialdirection; and a coil spring interposed between said holder and saidstop ring, for energizing said ferrule to the front in said plug frame,wherein said holder and said stop ring have engaging portions with whichthey are mutually engaged, and the entire of said stop ring is formed asa single substantially-cylindrical structure, and said stop ring isrotated round the axis in said plug frame and is fit while it isprevented from the movement in the axial direction.
 4. An opticalconnector plug according to claim 1, wherein the engaging portion ofsaid holder is a latching groove, and the engaging portion of said stopring is an engaging projection.
 5. An optical connector plug accordingto claim 2, wherein the engaging portion of said holder is a latchingprojection, and the engaging portion of said stop ring is a latchinggroove.
 6. An optical connector plug according to claim 3, wherein apair of latching holes, which penetrates a circumferential wall of saidplug frame to be opposed to each other, is provided and a ring-shapedprojected band for being fit into said latching hole is provided to acircumferential portion of said stop ring.